News TNMOC's EDSAC rebuild uncovers unique circuit diagrams

Discussion in 'Article Discussion' started by Gareth Halfacree, 25 Jun 2014.

  1. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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  2. Corky42

    Corky42 What did walle eat for breakfast?

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    Not that i am questioning the article, I'm just hoping to be educated :geek:

    A TV program i watched claimed America built and run the first GPC, obviously this article calls that into question and further research says it was the ENIAC in 1947.

    So have i been misinformed, duped by the TV, or have i misunderstood the label used to describe a general purpose computer ? Were the EDSAC and the ENIAC totally different animals ?
     
  3. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    It's something historians argue over. The general consensus is that while work was happening near-simultaneously on both projects, ENIAC went online first and is therefore the world's first general-purpose digital computer; EDSAC fans counter with the fact that ENIAC was arguably specialised for its military uses and was impractical to reprogram for other purposes, making EDSAC the world's first practical general-purpose digital computer (as the article states). Naturally, the American's don't like that argument - but the fact that EDSAC would lead to LEO, the very first commercial computer, lends the argument weight.

    EDIT: To add more detail, one of the biggest differences in practicality was that EDSAC was a stored-program computer, while ENIAC was not. Imagine if every time you switched your computer on you had to input the operating system and your chosen application manually. Using toggle-switches, or even jumper leads. That's where you were with ENIAC, while EDSAC could simply load a program into memory from punched tape. Here's a Wikipedia explanation:
    Contrast with EDSAC, which was simply "stick paper tape into reader and hit the MAKE PROGRAM GO button." Want to use ENIAC to do something else? Expect a couple of weeks at best to change programs. EDSAC? Pop to lunch and the operators will have it ready and running by the time you get back.
     
    Last edited: 25 Jun 2014
  4. Corky42

    Corky42 What did walle eat for breakfast?

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    Well i never, thanks for enlightening me :thumb:

    So it seems it's not who was first but more if ENIAC could even be classed as a GPC, it seems to me from your excellent explanation it was not. Well unless you consider having to spend a few weeks getting it to do something else.

    To think we used to complain about slow computers twenty odd years ago, just think of having to spend weeks just to change a program. :D
     
  5. jb0

    jb0 Member

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    That's actually somewhat misleading. The "The task of taking a problem and mapping it onto the machine was complex, and usually took weeks" is program development. the modern equivalent is coding software. This is not going to be appreciably different between ENIAC and EDSAC.

    "After the program was figured out on paper, the process of getting the program into ENIAC by manipulating its switches and cables could take days " is actual system configuration time once the program is developed, and this is where EDSAC improved upon ENIAC, both in terms of speed and reliability.

    Granted, a few days to "install" a program is still kind of ridiculous for general usage, and it pales before EDSAC's load times(which I expect to have been along the lines of a few minutes, though I seem unable to find actual numbers), but it's much shorter than a couple of weeks.




    Personally, I feel that the use of "practical" as a modifier in these sorts of comparisons is USUALLY just a way of wiggling around pre-existing work to claim you're first at something.
    But in EDSAC's case, I think it's fair, to the extent that it's unfortunate people wanting to claim they were first at something without actually BEING first at something have poisoned the word practical.




    And ENIAC, of course, is commonly misrepresented as the first computer instead of the first general-purpose computer(general-purpose is, of course, purely a representation of functionality, not practicality)
     
  6. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    True enough, that, and something I should have been clearer about - especially with my misleading closing paragraph.
    Remember, though, that while the paper-based development can take place while the system is running another program, the actual programming requires the system be down for several days.
    I certainly think it's fair, otherwise I'd never have included it in the article. The direct development from EDSAC to LEO kinda proves that; J. Lyons & Co. would never have tried to use an ENIAC-style system for business purposes, because it was entirely impractical.
     

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